CN112953331B - A harmonic suppression method for low-loss converter system of high-speed multi-phase permanent magnet synchronous motor - Google Patents

Abstract

The invention discloses a harmonic suppression method for a low-loss converter system of a high-speed multi-phase permanent magnet synchronous motor, which belongs to the technical field of new energy power generation and grid connection. Firstly, the phase shift angle between the multi-phase windings is determined by the harmonic suppression algorithm according to the number of phases, and then the harmonic components of the motor system in the process of active rectification and variable frequency speed regulation are suppressed through the harmonic suppression algorithm module, and then the Fourier Leaf analysis separates the mathematical expressions of harmful harmonics, establishes the current model in the rotating coordinate system, and suppresses them through the harmonic suppression link. Finally, the equivalent high switching frequency of the main power device is realized through the three-level main topology structure, and the drive control of the above harmonic suppression algorithm is performed. The invention can reduce the technical index requirements of the control system and the main power device, suppress the uncontrollable amplification effect of the multi-phase motor on the harmonics in the drive system; Fast response and stable operation driven by multi-phase motor converter.

Description

A harmonic suppression method for low-loss converter system of high-speed multi-phase permanent magnet synchronous motor

technical field

The invention belongs to the technical field of new energy power generation and grid connection, and in particular relates to a harmonic suppression method for a low-loss converter system of a high-speed multi-phase permanent magnet synchronous motor.

Background technique

Permanent magnet synchronous motors with permanent magnets as rotor materials have the advantages of convenient control, high energy conversion efficiency, simple structure, small size, and high energy density, and have a wide range of applications in high-speed and ultra-high-speed energy conversion and transmission fields. prospect. Due to the existence of harmonics in the generator and its driving system, a series of problems such as excessive generator shaft current, pitting corrosion of the gearbox, and heat generation are caused. The permanent magnets of high-power generator sets are easily demagnetized under high temperature and overload conditions, which seriously affect the performance of the generator set. In addition, system harmonics will also cause mechanical oscillation of the generator set and electrical oscillation between the generator set and the power grid, which greatly affects the safe and stable operation of the wind turbine. In order to continuously increase the high speed of the motor and reduce friction and heat generation, high-speed and high-power drives generally use magnetic bearing and vacuum cavity technology. While achieving high energy density, the problem of rotor heat dissipation is difficult. System heat dissipation and heat control have become important factors restricting the research and development of high-power and high-speed drive products. Restricted by the switching frequency of high-current silicon-based semiconductor devices and the high price of silicon carbide devices, high-speed and high-power converters use converters in parallel and IGBTs in parallel to achieve variable frequency speed regulation. Due to factors such as weak suppression ability, the internal harmonic content of the drive system is relatively large, resulting in serious heating of the high-power generator set itself.

In order to reduce the design pressure of high-speed and high-power motor-driven converters, the motor can be designed as a multi-winding motor, and the neutral point between the multi-windings is disconnected. In particular, the dual-winding phase-shifted 30° six-phase motor has an amplifying effect on a certain harmonic inside the motor and converter system for the application where the motor is in frequent switching operation between the motor and the power generation, which makes the harmonic suppression control difficult. The effect is not ideal. YY connection phase-shifting 30° between the two-winding motor windings three-phase related literature proposes that the harmonic suppression algorithm mainly relies on the high switching frequency of the main power device IGBT to finally achieve the harmonic suppression function, which contradicts the low rated switching frequency of the high-current IGBT. Some literatures propose the use of proportional resonance controller for harmonic control of multi-phase permanent magnet synchronous motors, but the proportional resonance controller has the disadvantages of narrow bandwidth and poor stability of pure integral link. Applications with large changes in wave frequency are likely to cause system instability, and it is difficult to achieve harmonic suppression effects. Some literatures propose the use of proportional resonance controller for harmonic control of multi-phase permanent magnet synchronous motors, but the proportional resonance controller has the disadvantages of narrow bandwidth and poor stability of pure integral link. Applications with a wide range of wave frequencies are likely to cause system instability. PI regulation can not well achieve no static error tracking control for harmonics, and the decoupling coordinate transformation in the multiple harmonic suppression algorithm has high requirements on the performance of the control system. Therefore, it is necessary to improve the design of the existing controller to meet the harmonic suppression requirements of the high-power permanent magnet synchronous motor drive system of the wind power system.

SUMMARY OF THE INVENTION

In order to solve the above problems, the purpose of the present invention is to provide a harmonic suppression method for a low-loss converter system of a high-speed multi-phase permanent magnet synchronous motor, which realizes the effective suppression of multiple over-limit harmonics in the drive system and reduces the heat generation of the flywheel motor. , reduces the torque ripple, reduces the radial electromagnetic polarization force of the rotor, reduces the loss of the permanent magnet synchronous motor, and improves the safety and stability of the high-speed dual-rotor generator equipment.

The present invention is achieved through the following technical solutions:

A harmonic suppression method for a low-loss converter system of a high-speed multi-phase permanent magnet synchronous motor, comprising:

S1: Calculate the phase shift angle between the windings according to the number of phases of the multiphase motor windings, and design the space structure of the multiphase motor windings according to the phase shift angle between the multiphase motor windings; according to the phase shift angle between the multiphase motor windings Calculate the phase shift angle of the modulated wave of the converter of the multi-phase motor drive system, and use the obtained phase shift angle of the modulated wave of the converter of the multi-phase motor drive system as the difference between the real-time electrical angles of the same-phase voltage and the different converters of the multi-phase motor. The real-time electrical angle difference of the in-phase voltage modulation wave of the converter drive system;

S2: According to the actual measurement value of the current of the same converter drive system of the multi-phase motor, separate the fundamental component and the harmonic component; separate the reference value "0" and the over-limit harmonic to be suppressed in the two-phase coordinate system. The quasi-proportional resonance adjustment, the adjustment result is subjected to 2/3 coordinate transformation as the harmonic suppression compensation amount, and then superimposed with the result of PI adjustment and coordinate transformation of the fundamental wave in the rotating coordinate system to generate the inverter drive system. modulated wave;

S3: The bridge arm of the multi-phase motor converter is connected in parallel with several IGBT switching devices, and the carrier phase shift angle is obtained according to the number of switching devices, and the carrier phase shift angle is taken as the electrical angle difference between the same bridge arm of the converter.

Preferably, in S1, the phase shift angle between the windings of the multi-phase motor

其中，m为电机相数。Phase Shift Angle of Modulated Wave of Converter in Multiphase Motor Drive System

Among them, m is the number of motor phases.

Preferably, in S2, the actual measured value of the current of the same converter drive system of the multi-phase motor is subjected to Fourier analysis to separate the fundamental wave component and the harmonic component.

Preferably, in S2, the quasi-proportional resonance adjustment is to perform quasi-proportional resonance adjustment for each harmonic current that needs to be suppressed and compensated, and then perform 2/3 coordinate transformation on the adjustment result of each harmonic current to generate each harmonic current. Compensated three-phase voltage reference value, and then superimpose all harmonic current compensation reference voltage value and fundamental wave current reference voltage value.

Further preferably, the mathematical relationship transfer function of the quasi-proportional resonance adjustment using the quasi-proportional resonance regulator is:

Among them, K _P is the proportional coefficient, K _jr is the resonance coefficient for suppressing a certain harmonic, ω _jc is the cut-off angular frequency for suppressing a certain harmonic, ω _j is the resonance frequency corresponding to different harmonics, ω _j =j*ω ₀ , ω ₀ is the fundamental angular frequency, j is the order of harmonics to be suppressed; where j = 3, 5, ..., m, ..., n, ω ₀ =dθ ₁ /dt, θ ₁ is the motor rotor relative to the stator a ₁ -phase winding real-time spatial position angle.

Preferably, in S2, the modulation wave of the converter drive system is the superposition value of the fundamental wave modulation wave and the real-time value of the reference value of each harmonic voltage to be suppressed, and its mathematical expression is:

u _{a, b, c} = u _{Fa1, Fb1, Fc1} +...+u _{Hma1, Hmb1, Hmc1} +...+u _{Hna1, Hnb1, Hnc1} ;

Among them, u _{a, b, c} are the three-phase modulated waves corresponding to the control signal of the inverter output three-phase voltage, u _{Fa1, Fb1, Fc1} are the three-phase modulated waves of the inverter output three-phase voltage corresponding to the fundamental control signal, u _{Hma1, Hmb1, Hmc1} are the three-phase modulated waves of the inverter output three-phase voltage corresponding to the m-th harmonic compensation control signal, u _{Hna1, Hnb1, Hnc1} are the inverter output three-phase voltage corresponding to the n-th harmonic compensation control signal three-phase modulated wave.

Preferably, in S3, the carrier phase shift angle γ ₃ =2π/ _NT , where _NT is the number of parallel IGBTs in the bridge arms of the multi-phase motor converter.

Preferably, in S3, a protection inductor is connected in series with the bridge arm of the multi-phase motor converter.

其中，U_DC为变流器直流母线电压值；f_T为三角载波频率；I_O为变流器输出电流值；N_T为桥臂并联IGBT个数；K_T为电感修正系数，取值范围1～1.5。Further preferably, the protection inductance

Among them, U _DC is the DC bus voltage value of the converter; f _T is the triangular carrier frequency; I _O is the output current value of the converter; N _T is the number of _IGBTs in parallel with the bridge arm; 1 to 1.5.

Preferably, in S3, the carrier phase shift adopts the SPWM generation method, and the high switching frequency voltage pulse waveform equivalent to the bridge arm is generated according to the comparison between the modulated wave and the carrier wave.

Compared with the prior art, the present invention has the following beneficial technical effects:

The harmonic suppression method for a low-loss converter system of a high-speed multi-phase permanent magnet synchronous motor disclosed in the present invention is influenced by three mutual coupling effects of the stator winding of the multi-phase motor, the core control algorithm of the converter, and the switching frequency of the main power device that performs power conversion. comprehensive solution. First of all, according to the principle of electromagnetic coupling between the stator windings of the motor, the reasonable phase shift angle between the windings is calculated to avoid the zero-crossing commutation point of the phase voltage and current between the stator windings of the multi-phase motor and the phase-to-phase commutation point overlapping, so that the The winding angle avoids the resonance amplification of a certain harmonic of the electric motor and the generator, so that the motor itself suppresses the generation of a certain harmonic to a certain extent. Secondly, based on Fourier analysis, the fundamental component and each harmonic component are separated, and then the mathematical expression of the over-limit harmonic is separated through the harmonic limit judgment link. Based on high-speed permanent magnet synchronous motor stator field-oriented vector control, the fundamental wave current is transformed by dq rotation coordinate, and the fundamental wave voltage reference value is generated through PI control. Perform two-phase coordinate transformation for each harmonic current that needs to be suppressed and compensated, perform quasi-proportional resonance (Q-PR) adjustment with the 0 reference value, perform no static error tracking control for each harmonic, and generate a harmonic current compensation reference voltage . The corresponding three-phase coordinate inverse transformation is performed on the fundamental wave current control voltage reference value and the harmonic current suppression compensation voltage reference value respectively, and the three-phase voltage reference values of the fundamental wave current and the harmonic current compensation value are respectively generated. Then, the fundamental current-controlled three-phase voltage reference value and the harmonic current compensation three-phase voltage reference value are superimposed to generate the total stator winding three-phase current control reference value and serve as the three-phase voltage modulation wave of the SPWM link. Finally, phase-shift control is performed on the carrier of the SPWM generation link to generate an equivalent high switching frequency high-frequency voltage that is _NT times the switching frequency of a single IGBT, and the effective implementation of the harmonic suppression algorithm is ensured through a reasonable equivalent switching frequency.

The invention combines software and hardware, is simple and practical, avoids the complex decoupling calculation of multiple harmonics, has obvious harmonic suppression effect on the high-speed and high-power permanent magnet synchronous motor of the new double-wind turbine wind generator system, and reduces the heating of the motor. , which improves the safety and stability of the high-speed dual-rotor generator system.

Description of drawings

Fig. 1 is the design schematic diagram of the phase shift angle between the windings of the high-speed multi-phase permanent magnet synchronous motor of the present invention;

FIG. 2 is a schematic diagram of the equivalent switching frequency of the carrier wave phase-shifting of the high-speed multi-phase permanent magnet synchronous motor of the present invention;

FIG. 3 is a schematic diagram of the harmonic separation, suppression and compensation method of the high-speed multi-phase permanent magnet synchronous motor of the present invention.

Detailed ways

The present invention will be further described in detail below with the accompanying drawings and specific embodiments, which are to explain rather than limit the present invention.

The invention is realized by combining Fourier analysis and SPWM generation method on the basis of high-speed motor vector control. Harmonic suppression is carried out from the three aspects of motor body stator winding design, core control algorithm and IGBT switching frequency. The combination of software and hardware achieves harmonic suppression target value control. Motor harmonic filtering and suppression are usually achieved by adding reactors, capacitors and other equipment, or increasing the motor's own inductance value to increase the harmonic tolerance, improving the modulation waveform in the control algorithm, and increasing the IGBT switching frequency to make the converter output. The waveform is as close to a sine as possible. None of these methods are suitable for harmonic suppression of high-speed and high-power motor systems.

Taking the high-power multi-phase motor as an example of a YY-30° connection six-phase dual-winding permanent magnet synchronous motor, the technical solution of the present invention is further explained:

Figure 1 shows the voltage waveform of a six-phase dual-winding motor with a phase shift of 30°, a ₁ , b ₁ , c ₁ and a ₂ , b ₂ , c ₂ are the three-phase voltage waveforms of winding 1 and winding 2 respectively. The intersection point of the three-phase voltage waveform under the same winding is the phase-to-phase commutation point of the three-phase current of the motor, and the zero-crossing point of the phase voltage is the natural commutation point of the phase current. These commutation points are a significant source of harmonics in three-phase systems. In Figure 1, the zero-crossing point of the three-phase voltage and phase voltage of winding 2 coincides with the forced commutation point between phases in the three-phase voltage of winding 1, and a coupling amplification path of a certain harmonic is formed through the motor stator magnetic field and the common DC bus. When this YY-30° connection six-phase double-winding permanent magnet synchronous motor is used as a dual-purpose motor for power generation and electric motor, the harmonic suppression control is more difficult, and there is no literature description.

计算得到YY-30°型接法六相双绕组电机的绕组间移相角度为15°，避免了多相电机绕组间电流换向点的重合，抑制了某次谐波的电磁耦合放大。依据公式

计算得到双绕组电机驱动变流器调制波的移相角度γ₂，这样双绕组电子电压的电角度与空间角度重合，双绕组电流形成和合成磁链接近正弦，减小了电机谐波畸变。According to the formula

It is calculated that the phase shift angle between the windings of the YY-30° connection six-phase double-winding motor is 15°, which avoids the overlap of the current commutation points between the windings of the multi-phase motor and suppresses the electromagnetic coupling amplification of a certain harmonic. According to the formula

The phase shift angle γ ₂ of the modulating wave of the double-winding motor drive converter is calculated, so that the electrical angle of the double-winding electronic voltage coincides with the spatial angle, the double-winding current and the combined magnetic link are close to sine, which reduces the harmonic distortion of the motor.

As shown in Figure 2, it is assumed that the same bridge arm is composed of three IGBTs in parallel, and c ₁ , c ₂ , and c ₃ are respectively the carrier signals of the three parallel IGBTs. The three carrier signals are compared with the modulating wave respectively to generate three PWM square wave signals, which are respectively used as the driving signals of the three IGBTs to drive the three parallel IGBTs to turn on and off. For this bridge arm, the three IGBT voltages that are not synchronously turned on synthesize the switching times higher than the consistent conduction, resulting in an equivalent high switching frequency and suppressing harmonics.

As shown in FIG. 3 , the current feedback values i _a1 , i _b1 , and i _c1 undergo Fourier analysis to separate the fundamental current components i _Fa1 , i _Fb1 , i _Fc1 and the harmonic current components of each order. Comparing the content of each harmonic current with the reference value k of harmonic current content, the main harmonic current values i _Hma1 , i _Hmb1 , i _Hmc1 , ..., i _Hna1 , i _Hnb1 , i _{Hnc1 are obtained} . . Where m and n represent the number of harmonics exceeding the limit value, m ≥ 3, and m is a positive integer. n≥m, and n is a positive integer. k is the percentage, which can be set according to the actual requirements of the high-power multi-winding drive system. Assuming that k=9%, the harmonics whose harmonic content exceeds 9% in the current will be suppressed and compensated respectively.

In the next step, the harmonic current values i _Hma1 , i _Hmb1 , i _Hmc1 , ..., i _Hna1 , i _Hnb1 , and i _Hnc1 are respectively subjected to 3/2 coordinate transformation, and the harmonic currents i _Hmα1 and i _Hmβ1 under the two-phase coordinates are obtained respectively, ..., i _Hnα1 , i _Hnβ1 .

In the next step, the harmonic currents i _Hmα1 , i _{Hmβ1 , .} Then, the 2/3 coordinate inverse transformation is performed on the results of the quasi-proportional resonance adjustment to obtain the harmonic compensation voltage values u _Hma1 , u _Hmb1 , u _Hmc1 , ..., u _Hna1 , u _Hnb1 , and u _Hnc1 . The quasi-proportional adjustment transfer function corresponding to each harmonic is:

In the formula, K _P is the proportional coefficient, K _jr is the resonance coefficient for suppressing a certain harmonic, ω _jc is the cut-off angular frequency for suppressing a certain harmonic, ω _j is the resonance frequency corresponding to different harmonics, ω _j =j* ω ₀ , ω ₀ is the angular frequency of the fundamental wave, and j is the order of harmonics to be suppressed; where j=3, 5, ..., m, ..., n, ω ₀ =dθ ₁ /dt, and θ ₁ is the relative value of the motor rotor relative to the Real-time spatial position angle of stator a ₁ -phase winding.

The transfer function of the quasi-proportional resonant regulator for the m-th current harmonic is:

The transfer function of the quasi-proportional resonant regulator for the nth current harmonic is:

The fundamental wave current components i _Fa1 , i _Fb1 , i _Fc1 are transformed by d and q rotation coordinates to obtain i _Fd1 , i _Fq1 , and then i _Fd1 , i _Fq1 are compared with the given values i _Fd1 ^ref , i _Fq1 ^ref and respectively PI adjustment is performed, and the d and q rotation coordinates are inversely transformed on the adjustment result to obtain the fundamental current adjustment reference voltage values u _Fna1 , u _Fnb1 , and u _Fnc1 .

Next, superimpose the reference voltages u _Fna1 , u _Fnb1 , u _Fnc1 on the corresponding compensation voltages u _Hma1 , u _Hmb1 , u _Hmc1 , ..., u _Hna1 , u _Hnb1 , u _Hnc1 respectively, to obtain the three-phase voltage control modulation of the converter 1 Waves u _a1 , u _b1 , u _c1 .

The next step is to compare the three-phase voltage-controlled modulation waves u _a1 , u _b1 , and u _c1 with the triangular carrier wave, and use the SPWM technology to generate the IGBT drive pulses of the main converter device of the converter. The triangular carrier corresponding to u _a1 , u _b1 , and u _c1 is generated according to the calculation of the carrier phase shifting technique.

The carrier phase shift angle θ ₂ =2π/n _T is obtained according to the number n _T of parallel switching devices in the converter, that is, if each bridge arm of the converter is operated by two IGBTs in parallel to undertake high-current switching, then n _T =2 , if three IGBTs are connected in parallel, n _T =3. In this way, the equivalent switching frequency is _nT times the switching frequency of a single IGBT, which further reduces the harmonic content of the system.

It should be noted that the above is only a part of the embodiments of the present invention, and equivalent changes made by the system described in the present invention are all included in the protection scope of the present invention. Those skilled in the art to which the present invention pertains can substitute the described specific examples in a similar manner, as long as they do not deviate from the structure of the present invention or go beyond the scope defined by the claims, they all belong to the protection scope of the present invention.

Claims (9)

1. a high-speed multi-phase permanent magnet synchronous motor low-loss converter system harmonic suppression method, is characterized in that, comprising: S1: Calculate the phase shift angle between the windings according to the number of phases of the multiphase motor windings, and design the space structure of the multiphase motor windings according to the phase shift angle between the multiphase motor windings; according to the phase shift angle between the multiphase motor windings Calculate the phase shift angle of the modulated wave of the converter of the multi-phase motor drive system, and use the obtained phase shift angle of the modulated wave of the converter of the multi-phase motor drive system as the difference between the real-time electrical angles of the same-phase voltage and the different converters of the multi-phase motor. The real-time electrical angle difference of the in-phase voltage modulation wave of the converter drive system; Phase shift angle between windings of a polyphase motor

Phase Shift Angle of Modulated Wave of Converter in Multiphase Motor Drive System

Among them, m is the number of motor phases; S2: According to the actual measurement value of the current of the same converter drive system of the multi-phase motor, separate the fundamental component and the harmonic component; separate the reference value "0" and the over-limit harmonic to be suppressed in the two-phase coordinate system. The quasi-proportional resonance adjustment, the adjustment result is subjected to 2/3 coordinate transformation as the harmonic suppression compensation amount, and then superimposed with the result of PI adjustment and coordinate transformation of the fundamental wave in the rotating coordinate system to generate the inverter drive system. modulated wave; S3: The bridge arm of the multi-phase motor converter is connected in parallel with several IGBT switching devices, and the carrier phase shift angle is obtained according to the number of switching devices, and the carrier phase shift angle is taken as the electrical angle difference between the same bridge arm of the converter; The polyphase motor is a six-phase two-winding phase-shifted 30° motor. 2. The harmonic suppression method for a low-loss converter system of a high-speed multi-phase permanent magnet synchronous motor as claimed in claim 1, wherein in S2, the actual measured value of the current of the same converter drive system of the multi-phase motor passes through Fourier transform Analysis to separate out the fundamental and harmonic components. 3. The harmonic suppression method of high-speed multiphase permanent magnet synchronous motor low-loss converter system as claimed in claim 1, characterized in that, in S2, the quasi-proportional resonance adjustment is to perform quasi-proportional resonance adjustment for each harmonic current that needs to be suppressed and compensated. Proportional resonance adjustment, and then perform 2/3 coordinate transformation of the adjustment results of each harmonic current to generate the three-phase voltage reference value for each harmonic current compensation, and then compare all harmonic current compensation reference voltage values with the fundamental current. The reference voltage values are superimposed. 4. high-speed multi-phase permanent magnet synchronous motor low-loss converter system harmonic suppression method as claimed in claim 3, is characterized in that, adopting the quasi-proportional resonance regulator to carry out the mathematical relation transfer function of quasi-proportional resonance adjustment is:

Among them, K _P is the proportional coefficient, K _jr is the resonance coefficient for suppressing a certain harmonic, ω _jc is the cut-off angular frequency for suppressing a certain harmonic, ω _j is the resonance frequency corresponding to different harmonics, ω _j =j*ω ₀ , ω ₀ is the fundamental angular frequency, j is the order of harmonics to be suppressed; where j = 3, 5, ..., m, ..., n, ω ₀ =dθ ₁ /dt, θ ₁ is the motor rotor relative to the stator a ₁ -phase winding real-time spatial position angle. 5. The method for suppressing harmonics in a low-loss converter system of a high-speed multiphase permanent magnet synchronous motor as claimed in claim 1, wherein in S2, the modulated wave of the converter drive system is the fundamental modulated wave and the one that needs to be suppressed. The superposition value of the real-time value of each harmonic voltage reference value, its mathematical expression is: u _{a, b, c} = u _{Fa1, Fb1, Fc1} +...+u _{Hma1, Hmb1, Hmc1} +...+u _{Hna1, Hnb1, Hnc1} ; Among them, u _{a, b, c} are the three-phase modulated waves corresponding to the control signal of the inverter output three-phase voltage, u _{Fa1, Fb1, Fc1} are the three-phase modulated waves of the inverter output three-phase voltage corresponding to the fundamental control signal, u _{Hma1, Hmb1, Hmc1} are the three-phase modulated waves of the inverter output three-phase voltage corresponding to the m-th harmonic compensation control signal, u _{Hna1, Hnb1, Hnc1} are the inverter output three-phase voltage corresponding to the n-th harmonic compensation control signal three-phase modulated wave. 6 . The method for suppressing harmonics of a low-loss converter system of a high-speed multiphase permanent magnet synchronous motor according to claim 1 , wherein in S3 , the carrier phase shift angle γ ₃ =2π/ _NT , and _NT is the polyphase The number of IGBTs connected in parallel with the bridge arm of the motor converter. 7 . The harmonic suppression method for a low-loss converter system of a high-speed multi-phase permanent magnet synchronous motor according to claim 1 , wherein, in S3 , a protection inductor is connected in series with the bridge arm of the converter of the multi-phase motor. 8 . 8. The harmonic suppression method for a low-loss converter system of a high-speed multiphase permanent magnet synchronous motor as claimed in claim 7, wherein the protection inductance is

Among them, U _DC is the DC bus voltage value of the converter; f _T is the triangular carrier frequency; I _O is the output current value of the converter; N _T is the number of _IGBTs in parallel with the bridge arm; 1 to 1.5. 9. The harmonic suppression method of high-speed multiphase permanent magnet synchronous motor low-loss converter system as claimed in claim 1, wherein in S3, the carrier phase shift adopts SPWM generation method, and the bridge is generated according to the comparison of modulated wave and carrier Arm equivalent high switching frequency voltage pulse waveform.

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